3d-formable sheet material

ABSTRACT

The present invention relates to a 3D-formable sheet material, a process for the preparation of a 3D-formed article, the use of a cellulose material and at least one particulate inorganic filler material for the preparation of a 3D-formable sheet material and for increasing the stretchability of a 3D-formable sheet material, the use of a 3D-formable sheet material in 3D-forming processes as well as a 3D-formed article comprising the 3D-formable sheet material according.

The present invention relates to a 3D-formable sheet material, a processfor the preparation of a 3D-formed article, the use of a cellulosematerial and at least one particulate inorganic filler material for thepreparation of a 3D-formable sheet material and for increasing thestretchability of a 3D-formable sheet material, the use of a 3D-formablesheet material in 3D-forming processes as well as a 3D-formed articlecomprising the 3D-formable sheet material according,

3D-formable materials are used in a great variety of applications suchas packaging container, e.g. medical and cosmetic packaging or foodpackaging, food container, e.g, candy boxes, blister pack, food tray andthe like. Paper-like materials, i.e. materials comprising a cellulosic,material, are becoming more and more attractive for such applicationsdue to their various advantages such as recyclability, biodegradabilityand renewability. Such materials are described in a number of documents.For instance, JP 2003-293282 A refers to a paper substrate moldable at<60° C. processing temperature without requiring preheating duringpressurized air molding or vacuum molding, easily carrying out disposaltreatment or recycling and utilization and having environmentallyexcellent properties. According to the working examples a polyacrylamidesystem is added to the pulp for preparing the paper substrate. JP2006-082384 A refers to a formable paper that is used as a substrate andan ink receiving layer which is disposed on the formable paper. The inkreceiving layer applied on the formable paper comprises a binding agentin order to prevent cracking. Especially preferred binding agents aredescribed as being a polyurethane copolymer, au acrylic copolymer, anethylene-vinyl acetate copoylmer and a rubber copolymer. CN 104015450 Arefers to a paper material comprising one or more layers, wherein thepaper material can be extended for at least 5% in a machine direction(MD) and can be extended for at least 5% in a cross direction (CD). Thepaper material is preferably a laminate, wherein the paper materials arebonded to each other by using a hinder, such as a water-based adhesivelayer, e.g. water-based glue, or PE. The PE or EVOH layer can be alsoused as moisture or gas barrier layer. CN 104015987 .A refers to aninsertion piece formed by a piece of extensible paper wood. Theinsertion piece is used for packaging and is in a three-dimensionalshape and formed by a piece of wood. The paper material is preferably alaminate, wherein the paper materials are bonded to each other by usinga binder, such as a water-based adhesive layer or PE. The PE layer isalso used as gas barrier layer. US 3,372,084 refers to a post-formableabsorbent paper adaptable to use in preparing post-formable plasticlaminates comprising in combination: a) a fiber portion containing from35 to 100% of fine fibers selected from vegetable fibers and syntheticorganic fibers, said fine fibers being characterized by having aspecific volume of 75 to 175 cubic microns per unit length and anaverage length of greater than. 2 mm, b) the remainder of the said fiberportion being selected from. paper making wood pulps, c) from 0.5 to30%, based on the total weight of said fiber portion, of an acidacceptor selected from zinc oxide, calcium carbonate and calciumsilicate, said paper being essentially neutral, as measured by the pH ofits water extract ranging from 6.8 to 7.6 with the alkali number of thewater extract ranging from 0.5 to 3.0, Also methods for forming3D-shaped articles are well known in the art, e.g. from WO 2015/063643A1, AU 54281/86 B, GB 2 092 941 A, US 7,681,733 B2, US 4,637,811 A, WO99/53810 Al, WO 2009/020805 A1, DE 10 2012 201 882 A1, US 1 567 162 andEP 2 829 392 A1,

However, poor 3D-formability of sheet materials is a limiting factor forpreparing 3D-formed articles. This poor 3D-formability typicallyoriginates from a limited strength of the sheet material and poorstretchability as well as the possible separation of fillers andcellulose material.

Therefore, there is a continuous need in the art for a 3D-formable sheetmaterial which provides good 3D-formability. in particular, there is aneed for a 3D-formable sheet material having sufficient strength andimproved stretchability as well as having a which mass is homogeneouslydistributed and such that its separation is complicated,

Accordingly, it is an objective of the present invention to provide a3D-formable sheet material which provides good 3D-formability for3D-formed articles. A further objective is to provide a 3D-formablesheet material having sufficient strength, i.e. the strength ismaintained or improved. Another objective is to provide a 3D-formablesheet material having a stretchability which is maintained or improved.An even further Objective is to provide a 3D-formable sheet material inwhich the mass is homogeneously distributed throughout the sheetmaterial and the separation of the components, especially of the fillerand cellulosic, material, is complicated.

The foregoing and other objectives are solved by the subject-matter asdefined herein in claim 1.

Advantageous embodiments of the inventive 3D-formable sheet material aredefined in the corresponding sub-claims.

According to one aspect of the present application a 3D-formable sheetmaterial is provided. The 3D-formable sheet material comprising

-   -   a) a cellulose material in an amount from 5 to 55 wt.-%, based        on the total dry weight of the 3D-formable sheet material,        wherein the cellulose material is a cellulose material mixture        comprising        -   i) nanofibrillated cellulose and/or microfibrillated            cellulose in an amount of ≥55 wt.-%, based. on the total dry            weight of the cellulose material mixture, and        -   ii) cellulose fibres in an amount of ≤45 wt.-%, based on the            total dry weight of the cellulose material mixture, and the            sum of the amount of the nanofibrillated cellulose and/or            microfibrillated cellulose and the cellulose fibres is 100            wt.-%, based on the total dry weight of the cellulose            material mixture, and    -   b) at least, one particulate inorganic filler material in an        amount of ≥45 wt.-%, based on the total dry weight of the        3D-formable sheet material,    -   wherein the sum of the amount of the cellulose material and the        at least one particulate inorganic filler material is 100.0        wt.-%, based on the total dry weight of the cellulose material        and the at least one particulate inorganic filler material.

The inventors surprisingly found out that the foregoing 3D-formablesheet material according to the present invention provides a good3D-formability for 3D-formed articles. More precisely, the inventorsfound that the foregoing 3D-formable sheet material according to thepresent invention provides sufficient strength and stretchability andthat its mass separation is complicated.

It should be understood that for the purposes of the present invention,the following terms have the following meanings:

The term “3D-formable” in the meaning of the present invention refers toa sheet material that can he formed into a 3D-formed article by using3D-forming processes such that the article retains the 3D form.

The term “3D-formed” article means that the article retains the 3D forminto which it has been formed from the 3D-formable sheet material.

The term “dry” with regard to the at least one particulate inorganicfiller material is understood to be a material having less than 0.3% byweight of water relative to the weight of the at least one particulateinorganic filler material. The % water is determined according to theCoulometric Karl Fischer measurement method, wherein the at least oneparticulate inorganic filler material is heated to 220° C., and thewater content released as vapour and isolated using a stream of nitrogengas (at 100 ml/min) is determined in a Coulometric Karl Fischer unit.

The term “dry” with regard to the cellulose material is understood to bea dry cellulose material having <0.5 % by weight of water relative tothe weight of the cellulose material. The “dry cellulose material” isdetermined by treating the cellulose material at 103° C. to constantweight in accordance with DIN 52 183.

The term “dry” with regard to the 3D-formable sheet material isunderstood to be a dry 3D-formable sheet material having <0.5% by weightof water relative to the weight of the 3D-formable sheet material. The“dry 3D-formable sheet material” is determined by treating the3D-formable sheet material at 103° C to constant weight in accordancewith DIN 52 183.

Where the term “comprising” is used in the present description andclaims, it does not exclude other non-specified elements of major orminor functional importance. For the purposes of the present invention,the term “consisting of” is considered to be a preferred embodiment ofthe term “comprising of”. If hereinafter a group is defined to compriseat least a certain number of embodiments, this is also to be understoodto disclose a group, which preferably consists only of theseembodiments.

Whenever the terms “including” or “having” are used, these terms aremeant to be equivalent to “comprising” as defined above.

Where an indefinite or definite article is used when referring to asingular noun, e.g. “a”, “an” or “the”, this includes a plural of thatnoun unless something else is specifically stated.

Terms like “obtainable” or “definable” and “obtained” or “defined.” areused interchangeably, This e.g. means that, unless the context clearlydictates otherwise, the term “obtained” does not mean to indicate that,e.g. an embodiment must be obtained by e.g. the sequence of stepsfollowing the term “obtained” even though such a limited understandingis always included by the terms “obtained” or “defined” as a preferredembodiment,

According to another aspect of the present invention, a process for thepreparation of a 3D-formed article is provided. The process comprisingthe steps of:

-   -   a) providing the 3D-formable sheet material as defined herein,        and    -   b) forming the 3D-formable sheet material into a 3D-formed        article, preferably by thermoforming, vacuum forming,        air-pressure forming, deep-drawing forming, hydroforming,        spherical forming, press forming, or vacuum/air-pressure        forming.

According to one embodiment of the process, the 3D-formable sheetmaterial has been obtained by

-   -   i) providing a cellulose material. as defined herein,    -   ii) forming a presheet consisting of the cellulose material of        step i), and    -   iii) drying the presheet of step ii) into a 3D-formable sheet        material.

According to another embodiment of the process, the cellulose materialof step i) is combined with at least one particulate inorganic, fillermaterial as defined herein to form a cellulose-inorganic filler materialmixture.

According to yet another embodiment of the process, i) the cellulosematerial is provided in form of an aqueous suspension comprising thecellulose material in a range from 0,2 to 35 wt.-%, more preferably 0.25to 20 wt.-%, even more preferably 0.5 to 15 wt.-%, most preferably I to10 wt-%, based on the total. weight of the aqueous suspension; and/orii) the at least one particulate inorganic filler material is providedin powder form, or in Rum of an aqueous suspension comprising theparticulate inorganic filler material in an amount from 1 to 80 wt-%,preferably from 5 to 78 wt.-%, more preferably from. 10 to 78 wt.-% andmost preferably from 15 to 78 wt.-%, based on the total weight of theaqueous suspension.

According to one embodiment of the process, the cellulose material is acellulose material mixture comprising nanofibrillated cellulose and/ormicrofibrillated cellulose that has been obtained by nanofibrillatingand/or microfibrillating a cellulose fibre suspension in the absence offillers and/or pigments, preferably the nanofibrillated cellulose and/ormicrofibrillated cellulose is in form of an aqueous suspension having aBrookfield viscosity in the range from 1 to 2 000 mPa·s at 25° C., morepreferably from 10 to 1 200 mPa·s at 25° C., and most preferably from100 to 600 mPa·s at 25° C. at a nanofibrillated cellulose and/ormicrofibrillated cellulose content of 1 wt. %, based on the total weightof the aqueous suspension.

According to another embodiment of the process, the cellulose materialis a cellulose material mixture comprising nanofibrillated celluloseand/or microfibrillated cellulose that has been obtained bynanofibrillating and; or microfibrillating cellulose fibre suspension inthe presence. of fillers and/or pigments, preferably the nanofibrillatedcellulose and/or microfibrillated cellulose is in form of an aqueoussuspension having a Brookfield viscosity in the range from 1 to 2 000mPa·s at 25° C., more preferably from 3 to 1 200 mPa·s at 25° C., andmost preferably from 10 to 600 mPa·s at 25° C., at a nanofibrillatedcellulose and/or microfibrillated cellulose content of 1 wt. %, based onthe total weight of the aqueous suspension.

From European patent applications EP 2 386 682 A1, EP 2 386 683 A1, EP 2236 664 A1, EP 2 236 545 A1, EP 2 808 440 A1, EP 2 529 942 A1 and EP 2805 986 A1, and from J. Rantanen et al., “Forming and dewatering of amicrofibrillated cellulose composite paper”, BioResources 10(2), 2015,pages 3492-3506, nanofibrillated and microfibrillated cellulose andtheir use in paper are known. However, there is no teaching with respectto their effects in 3D-formable sheet materials.

According to yet another embodiment of the process, the process furthercomprises a step c) of moisturizing the 3D-formable sheet materialprovided in step a) to a moisture content of 2 to 30 wt.-%, based on thetotal dry weight of the 3D-formable sheet material, before and/or duringprocess step b).

According to a. further aspect of the present invention, the use of acellulose material as defined herein and at least one particulateinorganic filler material as defined herein for the preparation of a3D-formable sheet material is provided. According to a still furtheraspect of the present invention, the use of a cellulose material asdefined herein and at least one particulate inorganic filler material asdefined herein for increasing the stretchability of a 3D-formable sheetmaterial is provided, wherein the increase is achieved when the3D-formable sheet material has a normalized stretch increase per levelof moisture content in the range from 0.15 to 0.7% per percent.According to an even further aspect of the present invention, the use ofa 3D-formable sheet material as defined herein in 3D-forming processesis provided, preferably in thermoforming, vacuum forming, air-pressureforming, deep-drawing forming, hydroforming, spherical forming, pressforming, or vacuum/air-pressure forming. According to another aspect ofthe present invention, a 3D-formed article, preferably a packagingcontainer, food container, blister pack, food tray, comprising the3D-formable sheet material, as defined herein, is provided.

According to one embodiment of the present invention, the 3D-formablesheet material comprises a) the cellulose material in an amount from 15to 55 wt.-%, based on the total dry weight of the 3D-formable sheetmaterial, and b) the at least one particulate inorganic filler materialin an amount from 45 to 85 wt.-%, based on the total dry weight of the3D-formable sheet material.

According to another embodiment of the present invention, the3D-formable sheet material has a) a normalized stretch increase perlevel of moisture content in the range from 0.15 to 0.7% per percent,and/or b) an elongation at break of at least 6 % preferably from 6 to16%, and most preferably from 7 to 15 % and/or c) a sheet weight from 50to 500 g/m², preferably from 80 to 300 g/m², and most preferably from 80to 250 g/m².

According to yet another embodiment of the present invention, thenanofibrillated cellulose and/or microfibrillated cellulose has beenobtained by nanofibrillating and/or microfibrillating a cellulose fibresuspension in the absence or presence of fillers and/or pigments,preferably the cellulose fibres of the cellulose fibre suspension aresuch contained in pulps selected from the group comprising softwoodpulp, such as spruce pulp and pine pulp, hardwood pulp, such aseucalyptus pulp. birch pulp, beech pulp, maple pulp, acacia pulp, andother types of pulp, such as hemp pulp, cotton pulp, bagasse or strawpulp, or recycled fiber material and mixtures thereof.

According to one embodiment of the present invention, the cellulosefibres a) are selected from the group comprising softwood fibres, suchas spruce fibres and pine fibres, hardwood fibres, such as eucalyptusfibres, birch fibres, beech fibres, maple fibres, acacia fibres, andother types of fibres, such as hemp fibres, cotton fibres, bagasse orstraw fibres, or recycled fiber material and mixtures thereof, and/or b)have a length weighted average fibre length from 500 μm to 3 000 μm.,more preferably from 600 μm to 2 000 μm, and most preferably from 700 to1 000 μm.

According to another embodiment of the present invention, the at leastone particulate inorganic filler material is at least one particulatecalcium carbonate-containing material, preferably the at least oneparticulate calcium carbonate-containing material is dolomite and/or atleast one ground calcium carbonate (GCC), such as marble, chalk,limestone and/or mixtures thereof, and/or at least one precipitatedcalcium carbonate (PCC), such as one or more of the aragonitic,vateritic and calcitic mineralogical crystal forms, more preferably theat least one particulate inorganic filler material is at least oneprecipitated calcium carbonate (PCC).

According to yet another embodiment of the present invention, the atleast one particulate inorganic filler material has a) a weight medianparticle size (d₅₀ from 0.1 to 20.0 μm, preferably in the range of 0.3to 10.0 μm, more preferably in the range of 0.4 to 8.0 μm, and mostpreferably in the range of 0.5 to 4.0 μm, and/or b) a specific surfacearea of from 0.5 to 200.0 m²/g, more preferably of from 0.5 to 100.0m²/g and most preferably of from 0.5 to 50.0 m²/g as measured by the BETnitrogen method.

As set out above, the inventive 3D-formable sheet material comprises acellulose material and at least one particulate inorganic fillermaterial set out in points a) and b), in the. following, it is referredto further details of the present invention and especially the foregoingpoints of the inventive 3D-formable sheet material.

According to the present invention, the 3D-formable. sheet materialcomprises

-   -   a) a cellulose material in an amount from 5 to 55 wt.-%, based        on the total dry weight of the 3D-formable sheet material, and    -   b) at least one particulate inorganic filler material in an        amount of ≥45 wt.-%, based on the total dry weight of the        3D-formable sheet material.

It is one requirement of the present 3D-formable sheet material that thesum of the amount of the cellulose material and the at least oneparticulate inorganic filler material is 100.0 wt.-%, based on the totaldry weight of the cellulose material and the at least one particulateinorganic filler material.

The 3D-formable sheet material of the present invention. comprises thecellulose material in an amount from 5 to 55 wt.-%, based on the totaldry weight of the 3D-formable sheet material. Preferably, the3D-formable sheet material comprises the cellulose material in an amountfrom 15 to 55 wt.-%, based on the total dry weight of the 3D-formablesheet material. For example, the 3D-formable sheet material comprisesthe cellulose material in an amount from 20 to 45 wt.-% or from 25 to 35wt.-%, based on the total dry weight of the 3D-formable sheet material,

Additionally, the 3D-formable sheet material comprises the at least oneparticulate inorganic filler material in an amount of 45 wt.-%, based onthe total dry weight of the 3D-formable sheet material. Preferably, the3D-formable sheet material comprises the at least one particulateinorganic filler material in an amount from 45 to 85 wt.-%, based on thetotal dry weight of the 3D-formable sheet material. For example, the3D-formable sheet material comprises the at least one particulateinorganic filler material in an amount from 55 to 80 wt.-% or from 65 to75 wt.-%, based on. the total dry weight of the 3D-formable sheetmaterial.

In one embodiment, the 3D-formable sheet material consists of thecellulose material and the at least one particulate inorganic fillermaterial. That is to say, the 3D-formable sheet material consists of

-   -   a) a cellulose material in an amount from 5 to 55 wt.-%,        preferably from 15 to 55 wt.-%, more preferably from 20 to 45        wt.-% or from 25 to 35 wt.-%, based on the total dry weight of        the 3D-formable sheet material, and    -   b) at least one particulate inorganic filler material in an        amount of≥45 wt.-%, preferably from 45 to 85 wt.-%, and most        preferably from 55 to 80 wt.-% or from 65 to 75 wt.-%, based on        the total dry weight of the 3D-formable sheet material,    -   wherein the sum of the amount of the cellulose material and the        at least one particulate inorganic filler material is 100.0        wt.-%, based on the total dry weight of the cellulose material        and the at least one particulate inorganic filler material.

it is appreciated that the 3D-formable sheet material may compriseadditives which are typically used in the field of paper manufacturingand especially 3D-formable sheet materials.

The term “at least one” additive in the meaning of the present inventionmeans that the additive comprises, preferably consists of, one or moreadditives.

In one embodiment of the present invention, the at least one additivecomprises, preferably consists of, one additive. Alternatively, the atleast one additive comprises, preferably consists of, two or moreadditives. For example, the at least one additive comprises, preferablyconsists of, two or three additives.

For example, the at least one additive is selected from the groupconsisting of a sizing agent, a paper-strength enhancer, a filler(differing from the at least one particulate inorganic filler material),a retention aid such as Percol®, a binder, a surfactant, a biocide anantistatic agent, a colorant and a flame retardant.

The at least one additive can be present in the 3D-formable sheetmaterial in an amount ranging from 0.01 to 10 wt.- %, based on the totaldry weight of the 3D-formable sheet material. For example, the at leastone additive can be present in the 3D-formable sheet material in anamount ranging from 0.02 to 8 wt.-%, preferably from 0,04 to 5 wt.-%,based on the total dry weight of the 3D-formable sheet material.

Thus, the 3D-formable sheet material may comprise

-   -   a) a cellulose material in an amount from 5 to 55 wt.-%,        preferably from 15 to 55 wt.-%, more preferably from 20 to 45        wt.-% or from 25 to 35 wt.-%, based on the total dry weight of        the 3D-formable sheet material,    -   b) at least one particulate inorganic filler material in an        amount of≥45 wt.-%, preferably from 45 to 85 wt.-%, and most        preferably from 55 to 80 wt.-% or from 65 to 75 wt.-%, based on        the total dry weight of the 3D-formable sheet material, and    -   c) optionally at least one additive in an amount from 0.01 to 10        wt.-%, preferably from 0.02 to 8 wt.-%, and most preferably from        0.04 to 5 wt.-%, based on the total dry weight of the        3D-formable sheet material,        wherein the sum of the amount of the cellulose material and the        at least one particulate inorganic filler material is 100.0        wt.-%, based on the total dry weight of the cellulose material        and the at least one particulate inorganic filler material.

In one embodiment, the 3D-formable sheet material consists of

-   -   a) a cellulose material in an amount from 5 to 55 wt.-%,        preferably from 15 to 55 wt.-%, more preferably from 20 to 45        wt.-% or from 25 to 35 wt.-%, based on the total dry weight of        the 3D-formable sheet material,    -   b) at least one particulate inorganic filler material in an        amount of ≥45 wt.-%, preferably from 45 to 85 wt.-%, and most        preferably from 55 to 80 wt.-% or from 65 to 75 wt.-%, based on        the total dry weight of the 3D-formable sheet material, and    -   c) optionally at least one additive in an amount from 0.01 to 10        wt.-%, preferably from 0.02 to 8 wt.-%, and most preferably from        0.04 to 5 wt.-%, based on the total dry weight of the        3D-formable sheet material,        Wherein the sum of the amount of the cellulose material and the        at least one particulate inorganic filler material is 100.0        wt.-%, based on the total dry weight of the cellulose material        and the at least one particulate inorganic filler material.

Thus, the 3D-formable sheet material preferably comprises the cellulosematerial and the at least one particulate inorganic filler material inan amount of ≥90 wt.-%, based on the total dry weight of the 3D-formablesheet material. For example, the 3D-formable sheet material preferablycomprises the cellulose material and the at least one particulateinorganic filler material in an amount of 90 to 99.99 wt.-%, based onthe total dry weight of the 3D-formable sheet material. Preferably, the3D-formable sheet material comprises the cellulose material and the atleast one particulate inorganic filler material in an amount of 92 to99.95 wt.-% or in an amount of 95 to 99.9 wt.-%, based on the total dryweight of the 3D-formable sheet material. Alternatively, the 3D-formablesheet material consists of the cellulose material and the at least oneparticulate inorganic filler material.

One advantage of the 3D-formable sheet material of the present inventionis that it features high stretchability as well as high elongation atbreak such that the 3D-formable sheet material is especially suitablefor preparing 3D-formed articles.

The 3D-formable sheet material especially features a high or increasedstretchability. In particular, it appreciated that the 3D-formable sheetmaterial has a normalized stretch increase per level of moisture contentin the range from 0.15 to 0.7% per percent. For example, the 3D-formablesheet material has a normalized stretch increase per level of moisturecontent in the range from 0.15 to 0.6% per percent sheet moisture andpreferably from 0.2 to 0.6%.

The “normalized stretch increase per level of moisture content” is amaterial property and is determined by the following formula (I)

$\begin{matrix}\frac{d({stretch})}{d({moisture})} & (I)\end{matrix}$

wherein d(moisture) defines the moisture content range considered, i.e,the difference between a higher moisture level of interest (e.g. 20%)and a lower moisture level of interest (e.g. 10%);d(stretch) defines the stretchability range at the moisture contentrange considered, i.e. the difference between the stretchability at thehigher moisture level of interest and the stretchability at the lowermoisture level of interest.

It is appreciated that the increased stretchability is dependent on themoisture content of the 3D-formable sheet material.

For example, the 3D-formable sheet material has a stretchability rangingfrom 4 to 10%, preferably from 5 to 10%, at a moisture content of 10% ofthe 3D-formable sheet material.

Additionally or alternatively, the 3D-formable sheet material has astretchability ranging from 6 to 18%, preferably from 7 to 18%, at amoisture content of 20% the 3D-formable sheet material.

The stretchability at specific moisture content can be determined by thefollowing formula II)

$\begin{matrix}{{{Stretchability}{at}X\%{moisture}} = {{\frac{d({stretch})}{d({moisture})}*{``{moisture}"}} + {{stretchability}{at}10\%{moisture}}}} & ({II})\end{matrix}$

wherein the “moisture” is defined as (X% moisture−%reference moisture)and the %reference moisture refers to the lower moisture level ofinterest.

It is appreciated that the 3D-formable sheet material may also feature ahigh or improved elongation at break. For example, the 3D-formable sheetmaterial has a elongation at break of at least 6%, preferably from 6 to16% and most preferably from 7 to 15%.

The 3D-formable sheet material preferably has a sheet weight from 50 to500 g/m², preferably from 80 to 300 g/m² and most preferably from 80 to250 g/m².

Thus, the 3D-formable sheet material preferably has

-   -   a) a normalized stretch increase per level of moisture content        in the range from 0.15 to 0.7% per percent, more preferably from        0.15 to 0.6% per percent and most preferably from 0.2 to 0.6 %        per percent, and/or    -   b) an elongation at break of at least 6%, more preferably from 6        to 16% and most preferably from 7 to 15%, and/or    -   c) a sheet weight from 50 to 500 g/m², more preferably from 80        to 300 g/m² and most preferably from 80 to 250 g/m².

For example, the 3D-formable sheet material preferably has

-   -   a) a normalized stretch increase per level of moisture content        in the range from 0.15 to 0.7% per percent, more preferably from        0.15 to 0.6 % per percent and most preferably from 0.2 to 0.6        per percent, and    -   b) an elongation at break of at least 6%, more preferably from 6        to 16% and most preferably from 7 to 15%, or    -   c) a sheet weight from 50 to 500 g/m², more preferably from 80        to 300 g/m² and most preferably from 80 to 250 g/m².

For example, the 3D-formable sheet material preferably has

-   -   a) a normalized stretch increase per level of moisture content        in the range from 0.15 to 0.7% per percent, more preferably from        0.15 to 0.6% per percent and most preferably from 0.2 to 0.6%        per percent, or    -   b) an elongation at break of at least 6%, more preferably from 6        to 16% and most preferably from 7 to 15%, and a sheet weight        from 50 to 500 g/m², more preferably from 80 to 300 g/m² and        most preferably from 80 to 250 g/m2,

In one embodiment, the 3D-formable sheet material has

-   -   a) a normalized stretch. increase per level of moisture content        in the range from 0.15 to 0.7% per percent, more preferably        from. 0.15 to 0.6% per percent and most preferably from 0.2 to        0.6% per percent, or    -   b) an elongation at break of at least 6° A, more preferably from        6 to 16% and most preferably from 7 to 15%, or    -   c) a sheet weight from 50 to 500 g/m², more preferably from 80        to 300 g/m² and most preferably from 80 to 250 g/m².

Preferably, the 3D-formable sheet material has

-   -   a) a normalized stretch increase per level of moisture content        in the range from 0.15 to 0.7% per percent, more preferably from        0.15 to 0.6% per percent and most preferably from 0.2 to 0.6%        per percent, and    -   b) an elongation at break of at least 6%, more preferably from 6        to 16% and most preferably from 7 to 15%, and    -   c) a sheet weight from 50 to 500 g/m², more preferably from 80        to 300 g/m² and most preferably from 80 to 250 g/m².

In the following the components of the 3D-formable sheet material aredescribed in more detail.

The cellulose material is a cellulose material mixturecomprising

-   -   i) nanofibrillated. cellulose and/or microfibrillated cellulose        in an amount of ≥55 wt.-%, based on the total dry weight of the        cellulose material mixture, and    -   ii) cellulose fibres in an amount of ≤45 wt.-%, based on the        total dry weight of the cellulose material mixture.

One requirement of the cellulose material mixture is that the sum of theamount of the nanofibrillated cellulose and/or microfibrillatedcellulose and the cellulose fibres is 100 wt.-%, based on the total dryweight of the cellulose material mixture.

The use of a nanofibrillated cellulose and/or microfibrillated cellulosehas the advantage that the separation of the at least one particulateinorganic filler material and the optional additives there iscomplicated such that a mass is obtained in which the single componentsare homogeneously distributed.

In one embodiment, the cellulose material mixture comprises

-   -   i) nanofibrillated cellulose or microfibrillated cellulose,        preferably microfibrillated cellulose, in an amount of ≥55        wt.-%, based on the total dry weight of the cellulose material        mixture, and    -   ii) cellulose fibres in an amount of ≤45 wt.-%, based on the        total dry weight of the cellulose material mixture,    -   and the sum of the amount of the nanofibrillated cellulose or        microfibrillated cellulose and the cellulose fibres is 100        wt.-%, based on the total dry weight of the cellulose material        mixture.

Alternatively, the cellulose material mixture comprises

-   -   i) nanofibrillated cellulose and microfibrillated cellulose in        an amount of ≥55 wt.-%, based on the total dry weight of the        cellulose material mixture, and    -   ii) cellulose fibres in an amount of ≤45 wt-%, based on the        total dry weight of the cellulose material mixture,    -   and the sum of the amount of the nanofibrillated cellulose and        microfibrillated cellulose and the cellulose fibres is 100        wt.-%, based on The total dry weight of the cellulose material        mixture.

Thus, the cellulose material mixture preferably comprises thenanofibrillated cellulose or microfibrillated cellulose, preferablymicrofibrillated cellulose, in an amount of ≥55 wt.-%, based on thetotal dry weight of the cellulose material mixture. For example, thecellulose material mixture comprises the nanofibrillated cellulose ormicrofibrillated cellulose, preferably microfibrillated cellulose, in anamount of 55 to 99 wt.-%, based on the total dry weight of the cellulosematerial mixture. Preferably, the cellulose material mixture comprisesthe nanofibrillated cellulose or microfibrillated cellulose, preferablymicrofibrillated cellulose, in an amount of 60 to 95 wt-% based on thetotal dry weight of the cellulose material mixture.

Additionally, the cellulose material mixture comprises the cellulosefibres in an amount of ≤45 wt.-%, based on the total dry weight of thecellulose material mixture. For example, the cellulose material mixturecomprises the cellulose fibres in an amount of 1 to 45 wt.-%, based onthe total dry weight of the cellulose material mixture. Preferably, thecellulose material mixture comprises the cellulose fibres in an amountof 5 to 40 wt.-%, based on the total dry weight of the cellulosematerial mixture.

In one embodiment, the weight ratio of nanofibrillated cellulose and/ormicrofibrillated cellulose to cellulose fibres in the cellulosematerial. mixture on a dry weight basis is from 90:10 to 50:50, morepreferably from 90:10 to 60:40 even more preferably from 90:10 to 70:30and most from 90:10 to 80:20, e.g. about 90:10 or about 85:15.

The terms “nanofibrillated cellulose” and “microfibrillated cellulose”refers to the commonly acknowledged definition, e.g. as defined in H.Sixta (Ed.), Handbook of Pulp, Wiley-VCH.

Cellulose pulp as a raw material is processed out of wood or stems ofplants such as hemp, linen and manila. Pulp fibres are built up mainlyby cellulose and other organic components (hemicellulose and lignin),The cellulose macromolecules (composed of 1-4 glycosidic linkedβ-D-Glucose molecules) are linked together by hydrogen bonds to form aso called nanofibril (also designated as primary fibril or micelle)which has crystalline and amorphous domains. Several nanofibrils (around55) form a so called microfibril. Around 250 of these microfibrils forma fibril.

The fibrils are arranged in different layers (which can contain ligninand/or hemicellulose) to form a fibre. The individual fibres are boundtogether by lignin as well.

When fibres become refined under applied energy they become fibrillatedas the cell walls are broken and torn into attached strips, i.e, intofibrils. if this breakage is continued to separate the fibrils from thebody of the fibre, it releases the fibrils. The breakdown of fibres intomicrofibrils is referred to as “micro fibrillation”. This process may becontinued until there are no fibres left and only nanofibrils remain.

If the process goes further and breaks these fibrils down into smallerand smaller fibrils, they eventually become cellulose fragments. Thebreakdown to nanofibrils may be referred to as “nano-fibrillation”,where there may be a smooth, transition between the two regimes.

The term “nanofibrillated cellulose” in the context of the presentinvention means fibres, which are at least partially broken down tonanofibrils (also designated as primary fibrils).

The term “microfibrillated cellulose” in the context of the presentinvention means fibres, which are at least partially broken down tomicrofibrils, The microfibrillated cellulose preferably has a Brookfieldviscosity in the range of from 1 to 2 000 mPa·s at 25° C., morepreferably from 10 to 1 200 mPa·s at 25° C., and most preferably from100 to 600 mPa·s at 25° C., at a nanofibrillated cellulose and/ormicrofibrillated cellulose content of 1 wt.-%, based on the total weightof the aqueous suspension.

In this respect, fibrillating in the context of the present inventionmeans any process which predominantly breaks down the fibres and fibrilsalong their long axis resulting in the decrease of the diameter of thefibres and fibrils, respectively. Nanofibrillated and microfibrillatedcelluloses and their preparation are well known to a person skilled inthe art. For example, nanofibrillated and microfibrillated cellulosesand their preparation are described in EP 2 386 682 A1, EP 2 386 683 A1,EP 2 236 664 A1 , EP 2 236 545 A1, EP 2 808 440 A1 and EP 2 805 986 A1which are thus incorporated herewith by references, as well as inFranklin W. Herrick, et al. “Microfibrillated Cellulose: Morphology andAccessibility”, Journal of Applied Polymer Science: Applied PolymerSymposium 37, 797-813 (1983), and Hubbe et al “Cellulosicnanocomposites, review” BioResources, 3(3), 929-890(208).

Preferably, the nanofibrillated cellulose and/or microfibrillatedcellulose has been obtained by nanofibrillating and/or microfibrillatinga cellulose fibre suspension in the absence or presence of fillersand/or pigments.

In one embodiment, the nanofibrillated cellulose and/or microfibrillatedcellulose has been obtained by nanofibrillating and/or microfibrillatinga cellulose fibre suspension in the absence of fillers and/or pigments.Thus, the nanofibrillated cellulose and/or microfibrillated cellulose isfree of fillers and/or pigments. Accordingly, the 3D-formable sheetmaterial is free of fillers and/or pigments differing from the at leastone particulate inorganic filler material in this embodiment,

The nanofibrillated cellulose and/or microfibrillated cellulose that hasbeen obtained by nanofibrillating and/or microfibrillating a cellulosefibre suspension in the absence of fillers and/or pigments, ispreferably in form of an aqueous suspension. Preferably, the aqueoussuspension has a Brookfield viscosity in the range from 1 to 2 000 mPa·sat 25° C., more preferably from 10 to 1 200 mPa·s at 25° C., and mostpreferably from 100 to 600 mPa·s at 25° C., at a nanofibrillatedcellulose and/or microfibrillated cellulose content of 1 wt.-%, based onthe total weight of the aqueous suspension.

In an alternative embodiment, the nanofibrillated cellulose and/ormicrofibrillated cellulose has been obtained by nanofibrillating and/ormicrofibrillating a cellulose fibre suspension in the presence offillers and/or pigments.

The fillers and/or pigments are preferably selected from the groupcomprising precipitated calcium carbonate (PCC); natural ground calciumcarbonate (GCC); dolomite; talc; bentonite; clay; magnesite; satinwhite; sepiolite, huntite, diatomite; silicates; and mixtures thereof,Precipitated calcium carbonate, which may have vateritic, calcitic oraragonitic crystal structure, and/or natural ground calcium carbonate,which may be selected from marble, limestone and/or chalk, areespecially preferred.

In a preferred embodiment, the use of natural ground calcium carbonate(GCC) such as marble, limestone and/or chalk as filler and/or pigmentmay be advantageous

It is appreciated that the 3D-formable sheet material may thus comprisein addition to the at least one particulate inorganic filler materialfurther fillers and/or pigments. The at least one particulate inorganicfiller material and the further fillers and/or pigments may be the sameor different. Preferably, the at least one particulate inorganic fillermaterial and the further fillers and/or pigments are different.

In one embodiment, the weight ratio of nanofibrillated cellulose and/ormicrofibrillated cellulose to fillers and/or pigments on a dry weightbasis is from 1:10 to 10:1, more preferably 1:6 to 6:1, typically 1:4 to4:1, especially 1:3 to 3:1, and most preferably 1:2 to 2:1, e.g. 1:1.

The nanofibrillated cellulose and/or microfibrillated cellulosepreferably comprises the fillers and/or pigments in amounts ranging from5 to 90 wt.-%, preferably from 20 to 80 wt.-%, more preferably from 30to 70 wt.-% and most preferably from 35 to 65 wt.-%, based on the totaldry weight of the nanofibrillated cellulose and/or microfibrillatedcellulose.

Thus, the cellulose material of the 3D-formable sheet materialpreferably comprises the fillers and/or pigments in amounts ranging from2 to 85 wt.-%, preferably from 2 to 70 wt.-%, more preferably from 3 to50 wt.-% and most preferably from 5 to 40 wt.-%, based on the total dryweight of the cellulose material. it is appreciated that the fillersand/or pigments derive from the nanofibrillating and/ormicrofibrillating of a cellulose fibre suspension in the presence offillers and/or pigments.

The nanofibrillated cellulose and/or microfibrillated cellulose that hasbeen obtained by nanofibrillating and/or microfibrillating a cellulosefibre suspension in the presence of fillers and/or pigments ispreferably in form of an aqueous suspension. Preferably, the aqueoussuspension has a Brookfield viscosity in the range from 1 to 2 000 mPa·sat 25° C., more preferably from 3 to 1 200 mPa·s at 25° C., and mostpreferably from 10 to 600 mPa·s at 25° C. at a nanofibrillated celluloseand/or microfibrillated cellulose content of 1 wl.%, based on. the totalweight of the aqueous suspension.

In a preferred embodiment, the filler and/or pigment particles have amedian particle size of from 0.03 to 15 μm, preferably 0.1 to 10 μm,more preferably 0.2 to 5 μm and most preferably 0.2 to 4 μm, e.g. 1.6 μmor 3.2 μm.

It is appreciated that the cellulose fibres of the cellulose fibresuspension from which the nanofibrillated cellulose and/ormicrofibrillated cellulose has been obtained are preferably suchcontained in pulps selected from the group comprising softwood pulp,such as spruce pulp and pine pulp, hardwood pulp, such as eucalyptuspulp, birch pulp, beech pulp, maple pulp, acacia pulp, and other typesof pulp, such as hemp pulp, cotton pulp, bagasse or straw pulp, orrecycled fiber material, and mixtures thereof.

The nanofibrillated cellulose and/or microfibrillated cellulose ispreferably obtained by nanofibrillating and/or microfibrillating acellulose fibre suspension in the presence of fillers and/or pigments.

The cellulose material mixture further comprises cellulose fibres.

The cellulose fibres present in the cellulose material mixture arepreferably selected from the group comprising softwood fibres, such asspruce fibres and pine fibres, hardwood fibres, such as eucalyptusfibres, birch fibres, beech fibres, maple fibres, acacia fibres, andother types of fibres, .such as hemp fibres, cotton fibres, bagasse orstraw fibres, or recycled fiber material and mixtures thereof.

It is appreciated that the cellulose fibres present in the cellulosematerial mixture may originate from the same or different fibres fromwhich the nanofibrillated cellulose and/or microfibrillated cellulosehave been obtained. Preferably, the cellulose fibres present in thecellulose material mixture originate from different fibres from whichthe nanofibrillated cellulose and/or microfibrillated cellulose has beenobtained,

In one embodiment, the cellulose fibres present in the cellulosematerial mixture are eucalyptus fibres.

It is appreciated that the cellulose fibres of the cellulose fibresuspension from which the nanofibrillated cellulose and/ormicrofibrillated cellulose has been obtained and the cellulose fibresmay be the same or different. Preferably, the cellulose fibres of thecellulose fibre suspension from which the nanofibrillated celluloseand/or microfibrillated cellulose has been obtained and the cellulosefibres are different.

Preferably, the cellulose fibres present in the cellulose materialmixture have a length weighted average fibre length from 500 μm to 3000μm, more preferably from 600 μm to 2 000 μm, and most preferably from700 to 1 000 μm.

Another essential component of the instant 3D-formable trial is at leastone particulate inorganic filler material.

The term “at least one” particulate inorganic filler material in themeaning of the present invention means that the particulate inorganicfiller material comprises, preferably consists of, one or moreparticulate inorganic filler materials,

In one embodiment of the present invention, the at least one particulateinorganic filler material comprises, preferably consists of, oneparticulate inorganic filler material. Alternatively, the at least oneparticulate inorganic filler material comprises, preferably consists of;two or more particulate inorganic filler materials. For example, the atleast one particulate inorganic filler material comprises, preferablyconsists of; two or three particulate inorganic filler materials.

Preferably, the at least one particulate inorganic filler materialcomprises, more preferably consists of, one particulate.

The term at least one “particulate” inorganic filler material in themeaning of the present invention refers to a solid compound thatcomprises, preferably consists of, the inorganic filler material.

The at least one particulate inorganic filler material may be aparticulate natural, synthetic or blended inorganic filler material suchas an. alkaline earth metal carbonate (e.g. calcium carbonate ordolomite), metal sulfate (e.g. barite or gypsum) metal silicate, metaloxide (e.g. titania or iron oxide), kaolin, calcined kaolin, talc ormica or any mixture or combination thereof.

Especially good results as regards the stretchability and the elongationat break are obtained in case the at least one particulate inorganicfiller material is at least one particulate calcium carbonate-containingmaterial.

The term “calcium carbonate-containing material” refers to a materialthat comprises at least 50.0 wt.-% calcium carbonate, based on the totalclay weight of the calcium carbonate-containing material,

According to one embodiment of the present invention, the at least oneparticulate calcium carbonate-containing material is selected fromdolomite, at least one ground calcium carbonate (GCC), at least oneprecipitated calcium carbonate (PCC) and mixtures thereof.

“Dolomite” in the meaning of the present invention is a carbonadocalcium-magnesium-mineral having the chemical composition of CaMg(CO₃)₂(“CaCO₃ MgCO₃”). Dolomite mineral contains at least 30.0 wt.-% MgCO₃,based on the total weight of dolomite, preferably more than 35.0 wt.-%,more than 40.0 wt.-%, typically from 45.0 to 46.0 wt.-% MgCO₃.

“Ground calcium carbonate” (GCC) in the meaning of the present inventionis a calcium carbonate Obtained from natural sources, such as limestone,marble or chalk, and processed through a wet and/or dry treatment suchas grinding, screening and/or fractionating, for example by a cyclone orclassifier.

According to one embodiment, the GCC is obtained by dry grinding.According to another embodiment of the present invention the GCC isobtained by wet grinding and subsequent drying.

In general, the grinding step can be carried out with any conventionalgrinding device, for example, under conditions such that refinementpredominantly results from impacts with a secondary body, i.e. in one ormore of: a ball mill, a rod mill, a vibrating mill, a roll crusher, acentrifugal impact mill, a vertical. bead mill, an attrition mill, a pinmill, a hammer mill, a pulveriser, a shredder, a de-clumper, a knifecutter, or other such equipment known to the skilled man. In casecalcium carbonate-containing material comprises a wet ground calciumcarbonate-containing material, the grinding step may be performed underconditions such that autogenous grinding takes place and/or byhorizontal ball milling, and/or other such processes known to theskilled man. The wet processed ground calcium carbonate-containingmaterial thus obtained may be washed and dewatered by well knownprocesses, e.g. by flocculation, filtration or forced evaporation priorto drying. The subsequent step of drying may be carried out in a singlestep such as spray drying, or in at least two steps. It is also commonthat such a calcium carbonate material undergoes a beneficiation step(such as a flotation, bleaching or magnetic separation step) to removeimpurities.

In one embodiment, the GCC is selected from the group comprising marble,chalk, limestone and mixtures thereof.

“Precipitated calcium carbonate” (PCC) in the meaning of the presentinvention is a synthesized material, generally obtained by precipitationfollowing reaction of carbon dioxide and lime in an aqueous environmentor by precipitation of a calcium and carbonate ion source in water. PCCmay be one or more of the aragonitic, vateritic and calciticmineralogical crystal forms. Preferably, PCC is one of the aragonitic,vateritic and calcitic mineralogical crystal. forms,

Aragonite is commonly in the acicular form, whereas vaterite belongs tothe hexagonal crystal system. Calcite can form scalenohedral,prismatic., spheral and rhombohedral forms. PCC can he produced indifferent ways, e.g. by precipitation with carbon dioxide, the lime sodaprocess, or the Solvay process in which PCC is a by-product of ammoniaproduction. The obtained PCC slurry can be mechanically dewatered anddried,

It is preferred that the at least one particulate inorganic fillermaterial is a particulate calcium carbonate-containing material being atleast one precipitated calcium carbonate (PCC), preferably at least oneprecipitated calcium carbonate (PCC) of the aragonitic, vateritic orcalcitic mineralogical crystal form.

In addition to calcium carbonate, the at least one particulate calciumcarbonate-containing material may comprise further metal oxides such astitanium dioxide and/or aluminium trioxide, metal hydroxides such asaluminium tri-hydroxide, metal salts such as sulfates, silicates such astalc and/or kaolin clay and/or mica, carbonates such as magnesiumcarbonate and/or gypsum, satin white and mixtures thereof.

According to one embodiment of the present invention, the amount ofcalcium carbonate in the at least one particulate calciumcarbonate-containing material is of ≥50.0 wt.-%, preferably of 90.0wt.-%, more preferably of ≥95.0 wt.-% and most preferably of ≥97.0 wt %,based on the total dry weight of the calcium carbonate-containingmaterial.

It is a preferred that the at least one particulate inorganic fillermaterial, preferably the at least one particulate calciumcarbonate-containing material, has a weight median particle size d₅₀from 0.1 to 20.0 μm, preferably in the range of 0.3 to 10.0 μm, morepreferably in the range of 0.4 to 8.0 μm, and most preferably in therange of 0.5 to 4.0 μm, e.g. 2.7 μm, as measured by the sedimentationmethod.

Throughout the present document, the “particle size” of a calciumcarbonate-comprising filler material or other particulate materials isdescribed by its distribution of particle sizes. The value d_(x)represents the diameter relative to which x % by weight of the particleshave diameters less than d_(x). This means that the d₂₀ value is theparticle size at which 20 wt.-% of all particles are smaller, and thed₉₈ value is the particle size at which 98 wt.-% of all particles aresmaller. The d₉₈ value is also designated as “top cut”. The d₅₀ value isthus the weight median particle size, i,e. 50 wt,--% of all grains aresmaller than this particle size. For the purpose of the presentinvention the particle size is specified as weight median particle sized₅₀ unless indicated otherwise. For determining the weight medianparticle size d₅₀ value or the top cut particle size d₉₈ value aSedigraph™ 5100 or 5120 device from the company Micromeritics, USA, canbe used. The method and the instrument are known to the skilled personand are commonly used to determine grain size of fillers and pigments.The measurement is carried out in an aqueous solution of 0.1 wt.-%Na₄P₂O₇. The samples are dispersed using a high speed stirrer andsupersonics.

The at least one particulate Moronic filler material, preferably the atleast one particulate calcium carbonate-containing material, may have atop cut, for example, of below 40.0 μm. Preferably, the at least oneparticulate inorganic filler material, preferably the at least oneparticulate calcium carbonate-containing material, has a top cut ofbelow 30.0 μm and more preferably of below 20.0 μm.

Additionally or alternatively, the at least one particulate inorganicfiller material, preferably the at least one particulate calciumcarbonate-containing material, has a specific surface area of from 0.5to 200.0 m²/g, more preferably of from 0.5 to 100.0 m²/g and mostpreferably of from 0.5 to 50.0 m²/g as measured by the BET nitrogenmethod.

The term “specific surface area” (in m²/g) of the at least oneparticulate calcium carbonate-containing material in the meaning of thepresent invention is determined using the BET method, which is wellknown to the skilled man (ISO 9277:1995).

It is appreciated that the 3D-formable sheet material is preferably freeof layers/laminates comprising polymeric materials which are suitablefor improving the stretchability and the elongation at break of thesheet material. Thus, the 3D-formable sheet material is preferably freeof (synthetic) polymeric materials such as PE, PP, EVOH and the like.

According to another aspect of the present invention, a process for thepreparation of a 3D-formed article is provided. The process comprisingthe steps of:

-   -   a) providing the 3D-formable sheet material as defined herein,        and    -   b) forming the 3D-formable sheet material into a 3D-formed        article.

With regard to the definition of the 3D-formable sheet material andpreferred embodiments thereof, reference is made to the statementsprovided above when discussing the technical details of the 3D-formablesheet material of the present invention.

The forming of the 3D-formable sheet material into a 3D-formed. articlemay be undertaken by all the techniques and. process lines well known tothe man skilled in the art for farming 3D-formed articles. However, itis appreciated that pressure forming processes according to DIN 8583 aretypically not suitable for forming the 3D-formable sheet material into a3D-formed article.

The 3D-formed articles are preferably formed in a tensile compressionforming process according to DIN 8584 or a tensile forming processaccording to DIN 8585.

The forming of the 3D-formable sheet material into a 3D-formed articleis preferably carried out by thermoforming, vacuum forming, air-pressureforming, deep-drawing forming, hydroforming, spherical forming, pressforming, or vacuum/air-pressure forming. These techniques are well knownto the man skilled in the art for forming 3D-formed articles.

It is preferred that the 3D-formable sheet material which is formed intoa 3D-formed article should have specific moisture content in order tofacilitate the forming process in step b). In particular, it ispreferred that the 3D-formable sheet material provided in step a) has amoisture content of ≥2 wt.-%, based on the total dry weight of the3D-formable sheet material. However, if the moisture content exceeds aspecific value, the quality of the resulting 3D-formed article typicallydeteriorates, Thus, it is preferred that the 3D-formable sheet materialprovided in step a) has a moisture content of ≤30 wt.-%, based on thetotal dry weight of the 3D-formable sheet material.

Thus, the 3D-formable sheet material provided in step a) preferably hasa moisture content in the range from 2 to 30 wt.-%, based on the totaldry weight of the 3D-formable sheet material. For example, the3D-formable sheet material provided in step a) preferably has a moisturecontent in the range from 6 to 25 wt.-% or from 10 to 20 wt.-%, based onthe total dry weight of the 3D-formable sheet material.

In case the moisture content of the 3D-formable sheet material providedin step a) is ≤2 wt.-% or ≥30 wt.-%, based on the total dry weight ofthe 3D-formable sheet material, the 3D-formable sheet material may thusbe moisturized.

In one embodiment, the process thus further comprises a step c) ofmoisturizing the 3D-formable sheet material provided in step a) to amoisture content of 2 to 30 wt.-%, based on the total dry weight of the3D-formable sheet material. Preferably, step c) is carried out such thatthe 3D-formable sheet material is moisturized to a moisture content of 6to 25 wt.-% or of 10 to 20 wt.-%, based on the total dry weight of the3D-formable sheet material.

It is appreciated that the moisture content after moisturizing isdetermined according to common practice, i.e. the moisture content ispreferably not determined immediately after moisturizing. Preferably,the moisture content after moisturizing is determined as soon as amoisture equilibrium in the 3D-formable sheet material is achieved.Methods for obtaining and determining such moisture equilibrium are wellknown to the person skilled in the art.

For example, the moisture content is determined at least 30 min aftermoisturizing the 3D-formable sheet material. Preferably, the moisturecontent is determined 30 min to 24 h, e.g. 1 h to 24 h, aftermoisturizing the 3D-formable sheet material.

Moisturizing step c) is preferably carried out before and/or duringprocess step b). In one embodiment, moisturizing step c) is carried outbefore and during process step b). Alternatively, moisturizing step c)is carried out before or during process step b). For example,moisturizing step c) is carried out before process step b).

The moisturizing of the 3D-formable sheet material may be undertaken byall the methods and instruments well known to the man skilled in the artfor moisturizing materials. For example, the moisturizing of the3D-formable sheet material can be carried out by spraying.

It is preferred that the 3D-formable sheet material has been obtained by

-   -   i) providing a cellulose material, as defined herein,    -   ii) forming a presheet consisting of the cellulose material of        step i), and    -   iii) drying the presheet of step ii) into a 3D-formable sheet        material.

If the 3D-formable sheet material comprises additives, the cellulosematerial is combined with the additives in step i).

In one embodiment, the cellulose material is combined with at least oneparticulate inorganic filler material as defined herein to form acellulose-inorganic filler material mixture. It is appreciated that thisembodiment preferably applies where the cellulose material does notcomprise tiller and/or pigments, If the 3D-formable sheet materialcomprises additives, the cellulose material is combined with the atleast one particulate inorganic filler material and the additives instep i) to form a cellulose-inorganic filler material mixture.

With regard to the definition of the cellulose material, the at leastone particulate inorganic filler material, the additives and preferredembodiments thereof, reference is made to the statements provided aboveWhen discussing the technical details of the 3D-formable sheet materialof the present invention.

The cellulose material is preferably provided in form of an aqueoussuspension. For example, an aqueous suspension comprising the cellulosematerial in a range from 0,2 to 35 wt.-%, more preferably 0.25 to 20wt.-%, even more preferably 0.5 to 15 wt.-%, most preferably 1 to 10wt-%, based on the total weight of the aqueous suspension.

In one embodiment, the cellulose material is a nanofibrillated celluloseand/or microfibrillated cellulose that has been obtained bynanofibrillating and/or microfibrillating a cellulose fibre suspensionin the absence or presence of fillers and/or pigments.

If the cellulose material is a nanofibrillated cellulose and/ormicrofibrillated cellulose that has been obtained. by nanofibrillatingand/or microfibrillating a cellulose fibre suspension in the presence offillers and/or pigments, the fillers and/or pigments and the at leastone particulate inorganic filler material may be the same. That is tosay, the fillers and/or pigments are the at least one particulateinorganic filler material. In this embodiment, the cellulose material isthus preferably not further combined with the at least one particulateinorganic filler material.

In another preferred embodiment, the cellulose material is ananofibrillated cellulose and/or microfibrillated cellulose that hasbeen obtained by nanofibrillating and/or microfibrillating a cellulosefibre suspension in the absence or presence of fillers and/or pigmentsand the cellulose material is further combined with the at least oneparticulate inorganic filler material.

In any case, the cellulose material provided comprises fillers and/orpigments and/or the cellulose material is combined. with the at leastone particulate inorganic filler material such that the 3D-formablesheet material comprises the at least one particulate inorganic fillermaterial in an amount of ≥45 wt.-% based on the total dry weight of the3D-formable sheet material.

If the cellulose material is combined with the at least one particulateinorganic filler material, the at least one particulate inorganic fillermaterial is provided in powder form, i.e. in dry form, or in form of anaqueous suspension.

If the at least one particulate inorganic filler material is provided inform of an aqueous suspension, the aqueous suspension comprises theparticulate inorganic filler material preferably in an amount from 1 to80 wt.-%, more preferably from 5 to 78 wt.-%, even more preferably from10 to 78 wt.-% and most preferably from 15 to 78 wt.-%, based on thetotal weight of the aqueous suspension.

In one embodiment, the cellulose material is provided in the form of anaqueous suspension and the at least one particulate inorganic fillermaterial is provided in form of an aqueous suspension.

Alternatively, the cellulose material is provided in the form of anaqueous suspension and the at least one particulate inorganic fillermaterial is provided in powder form.

An aqueous “slurry” or “suspension” in the meaning of the presentinvention comprises insoluble solids and water and usually may containlarge amounts of solids and, thus, can be more viscous and generally ofhigher density than the liquid from which it is formed.

The term “aqueous” slurry or suspension refers to a system, wherein theliquid phase comprises, preferably consists of, water. However, saidterm does not exclude that the liquid phase of the aqueous slurry orsuspension comprises minor amounts of at least one water-miscibleorganic solvent selected from the group comprising methanol, ethanol,acetone, acetonitrile, tetrahydrofuran and mixtures thereof. If theaqueous slurry or suspension comprises at least one water-miscibleorganic solvent, the liquid phase of the aqueous slurry comprises the atleast one water-miscible organic solvent in an amount of from 0.1 to40.0 wt.-% preferably from 0.1 to 30.0 wt.-%, more preferably from 0.1to 20.0) wt.-% and most preferably from 0.1 to 10.0 wt.-%, based on thetotal weight of the liquid phase of the aqueous slurry or suspension.For example, the liquid phase of the aqueous slurry or suspensionconsists of water. If the liquid phase of the aqueous slurry orsuspension consists of water, the water to be used can be any wateravailable such as tap water and/or deionised water.

The cellulose material is combined with the at least one particulateinorganic filler material and the optional additives in any order.Preferably, the at least one particulate inorganic filler material andthe optional additives are added to the cellulose material.

The cellulose material is a cellulose material mixture comprisingnanofibrillated cellulose and/or microfibrillated cellulose.

Preferably, the cellulose material is a cellulose material mixturecomprising nanofibrillated cellulose and/or microfibrillated cellulosethat has been obtained by nanofibrillating and/or microfibrillating acellulose fibre suspension in the absence or presence of fillers and/orpigments.

In case the nanofibrillated cellulose and/or microfibrillated cellulosehas been obtained. by nanofibrillating and/or microfibrillating acellulose fibre suspension in the absence of fillers and/or pigments,the nanofibrillated cellulose and/or microfibrillated cellulose ispreferably in form of an aqueous suspension having a Brookfieldviscosity in the range from 1 to 2 000 mPa·s at 25° C., more preferablyfrom 10 to 1 200 mPa·s at 25° C., and most preferably from 100 to 600mPa·s at 25° C., at a nanofibrillated cellulose and/or microfibrillatedcellulose content of 1 wt.-%, based on the total weight of the aqueoussuspension.

In case the nanofibrillated cellulose and/or microfibrillated cellulosehas been obtained by nanofibrillating and/or microfibrillating acellulose fibre suspension in the presence of fillers and/or pigments,the nanofibrillated cellulose and/or microfibrillated cellulose ispreferably in form of an aqueous suspension having a Brookfieldviscosity in the range from 1 to 2 000 mPa·s at 25° C., more preferablyfrom 3 to 1 200 mPa·s at 25° C., and most preferably from 10 to 600mPa·s at 25° C., at a nanofibrillated cellulose and/or microfibrillatedcellulose content of 1 wt.-%) based on the total weight of the aqueoussuspension.

The aqueous suspension of the nanofibrillated cellulose and/ormicrofibrillated cellulose preferably comprises the nanofibrillatedcellulose and/or microfibrillated cellulose in an amount from 0.2 to 35wt.-%, more preferably 0.25 to 20 wt.-%, even more preferably 0.5 to 15wt.-%, most preferably 1 to 10 wt-%, based on the total weight of theaqueous suspension.

Processes for preparing nanofibrillated and microfibrillated cellulosesare well known to a person skilled in the art. For example, processesfor preparing nanofibrillated and microfibrillated celluloses aredescribed in EP 2 386 682 A1, EP 2 386 683 A1, EP 2 236 664 A1, EP 2 236545 A1, EP 2 808 440 A1 and EP 2 805 986 A1 which are thus incorporatedherewith by references, as well as in Franklin W. Herrick, et al.“Microfibrillated Cellulose: Morphology and Accessibility”, Journal ofApplied Polymer Science: Applied Polymer Symposium 37, 797-813 (1983),and Hubbe et al “Cellulosic nanocomposites, review” BioResources, 3(3),929-890 (2008).

It is appreciated that the term. “cellulose-inorganic filler materialmixture” refers to a mixture of the cellulose material, the at least oneparticulate inorganic filler material and the optional additives.Preferably, the cellulose-inorganic filler material mixture is ahomogeneous mixture of the cellulose material, the at least oneparticulate inorganic filler material and the optional additives.

The cellulose-inorganic filler material mixture is preferably an aqueoussuspension comprising the cellulose material, the at least oneparticulate inorganic filler material and the optional additives. In oneembodiment, the aqueous suspension of the cellulose-inorganic fillermaterial mixture has solids content in the range from 0.3 to 35 wt.-%,more preferably 0.5 to 30 wt.-%, even more preferably 0.7 to 25 wt.-%,most preferably 0.9 to 20 wt-%, based on the total weight of the aqueoussuspension.

According to step ii) of the process, a presheet consisting of thecellulose-inorganic filler material mixture of step i) is formed.

The forming step ii) may be undertaken by all the techniques and methodswell known to the man skilled in the art for forming a presheet of thecellulose-inorganic filler material mixture. The forming step ii) may becarried out with any conventional forming machine, for example, underconditions such that a. continuous or dicontinuous presheet of thecellulose-inorganic filler material mixture is obtained or other suchequipment known to the skilled person. For example, the forming can becarried out in a paper machine as described in J. Rantanen, et al.,Forming and dewatering of a microfibrillated cellulose composite paper.BioRes. 10(2), 2015, 3492-3506.

The presheet of the cellulose-inorganic filler material mixture can besubjected to a step of reducing the water content of the presheet, Suchstop of reducing the water content can be carried out during or after,preferably after, process step ii). Such step of reducing the watercontent may he undertaken by all the techniques and methods well knownto the man skilled in the art far reducing the water content of apresheet. The step of reducing the water content may be carried out withany conventional method, e.g. by pressure, wet pressing vacuum, force ofgravity or suction power such that a presheet having a water contentthat is reduced compared to the water content before the step ofreducing the water content is obtained or other such equipment known tothe skilled person.

Unless specified otherwise, the term “reducing the water content” refersto a process according to which only a portion of water is removed fromthe presheet such that a predried presheet is obtained. Moreover, a“predried” presheet may be further defined by its total moisture contentwhich, unless specified otherwise, is more than or equal to 5 wt.-%,preferably more than or equal to $wt.-%, more preferably more than orequal to 10 wt.-%, and most preferably from 20 to 60 wt.-%, based on thetotal weight of the presheet.

Thus, the process preferably further comprises a step iv1) of dewateringthe presheet of step ii).

In one embodiment, the dewatering of step iv1) is carried out underpressure, preferably under pressure in the range from 10 to 150 kPa,more preferably under a pressure in the range from 20 to 100 kPa, andmost preferably under a pressure in the range from 30 to 80 kPa.

Alternatively, the process further comprises a step iv2) of wet pressingthe presheet of step ii).

In one embodiment, the presheet obtained in step iv1) is farthersubjected to a step of wet pressing in order to further reduce the watercontent. In this ease, the process further comprises a step iv2) of wetpressing the presheet of step iv1).

Wet pressing step iv2) is preferably carried out under pressure in therange from 100 to 700 kPa, preferably under pressure in the range from200 to 600 kPa, and most preferably under pressure in the range from 300to 500 kPa. Additionally or alternatively, wet pressing step iv2) iscarried out at a temperature in the range from 10 to 80° C., preferablyat a temperature in the range from 15 to 75° C., and more preferably ata temperature in the range from 20 to 70° C.

Preferably, step iv2) of wet pressing the presheet of step ii) or ofstep iv1) is carried out under a pressure in the range from 100 to 700kPa, preferably under a pressure in the range from 200 to 600 kPa, andmost preferably under a pressure in the range from 300 to 500 kPa, andat a temperature in the range from 10 to 80° C., preferably at atemperature in the range from 15 to 75° C., and more preferably at atemperature in the range from 20 to 70° C.

According to step iii), the presheet of step ii) or of step iv1) or ofstep iv2) is dried into a 3D-formable sheet material.

The term “drying” refers to a process according to which at least aportion of water is removed from the presheet. such that a 3D-formablesheet material is obtained. Moreover, a “dried” 3D-formable sheetmaterial may be further defined by its total moisture content which,unless specified otherwise, is less than or equal to 30 wt.-%,preferably less than or equal to 25 wt.-%, more preferably less than orequal to 20 wt.-%, and most preferably less than or equal5 wt.-%, basedon the total weight of the dried material.

Such step of drying may be undertaken by all the. techniques and methodswell known to the man. skilled in the art for drying a presheet. Thestep of drying may be carried out with any conventional method, e.g. bypressure, force of gravity or suction power such that a presheet havinga water content that is reduced compared to the water content before thedrying is obtained or other such equipment known to the skilled person..

In one embodiment, step iii) is carried out by press drying. Forexample, by press drying under a pressure in the range from 50 to 150kPa, preferably under a pressure in the range from 60 to 120 kPa, andmost preferably under a pressure in the range from 80 to 100 kPa, and/orat a temperature in the range from 80 to 180° C., preferably at atemperature in the range from 90 to 160° C., and more preferably at atemperature in the range from 100 to 150° C.

In one embodiment, step iii) is carried out by press drying under apressure in the range from 50 to 150 kPa, preferably under a pressure inthe range from 60 to 120 kPa, and most preferably under a pressure inthe range from. 80 to 100 kPa, and at a temperature in the range from 80to 180° C., preferably at a temperature in the range from 90 to 160° C.,and more preferably at a temperature in the range from 100 to 150° C.

In view of the very good results of the 3D-formable sheet material asdefined above, a further aspect of the present invention refers to theuse of a cellulose material as defined herein and at least oneparticulate inorganic filler material as defined herein. for thepreparation of a 3D-formable sheet material.

Another aspect of the present invention refers to the use of a cellulosematerial as defined herein and at least one particulate inorganic fillermaterial as defined herein for increasing the stretchability of a3D-formable sheet material, wherein the increase is achieved when the3D-formable sheet material has a normalized stretch increase per levelof moisture content in the range from 0.15 to 0.7% per percent. Thenormalized stretch increase per level of moisture content is preferablydetermined in accordance with formula (I) defined above.

In one embodiment, the increase is achieved when the 3D-formable sheetmaterial has a normalized stretch increase per level of moisture contentin the range from 0.15 to 0.6% per percent and most preferably from 0.2to 0.6% per percent. The normalized stretch increase per level ofmoisture content is preferably determined in accordance with formula (I)outlined above.

In one embodiment, the 3D-formable sheet material has a stretchabilityranging from 4 to 10%, preferably from 5 to 10%, at a moisture contentof 10% of the 3D-formable sheet material. Additionally or alternatively,the 3D-formable sheet material has a stretchability ranging from 6 to18%, preferably from 7 to 18%, at a moisture content of 20% of the3D-formable sheet material. The stretchability is preferably determinedin accordance with formula (II) outlined above.

A still further aspect of the present invention refers to the use of a3D-formable sheet material as defined herein in 3D-forming processes.Preferably, the present invention refers to the use of a 3D-formablesheet material as defined herein in thermoforming, vacuum forming,air-pressure forming, deep-drawing forming, hydroforming, sphericalforming, press forming, or vacuum/air-pressure forming,

A further aspect of the present invention refers to a 3D-formed article,preferably a packaging container, food container, blister pack, foodtray, comprising the 3D-formable sheet material as defined herein.

With regard to the definition of the cellulose material, the at leastone particulate inorganic filler material, the 3D-formable sheetmaterial and preferred embodiments thereof, reference is made to thestatements provided above when discussing the technical details of the3D-formable sheet material of the present invention.

DESCRIPTION OF THE FIGURES

FIG. 1 shows microfibrillated cellulose prepared in the presence of GCCparticles.

FIG. 2 shows microfibrillated cellulose prepared in the absence offiller and/or pigments.

FIG. 3 refers to a diagram showing the relationship of stretch andmoisture.

The following examples may additionally illustrate the invention but arenot meant to restrict the invention to the exemplified embodiments. Theexamples below show the 3D-formable sheet material and its excellentgood mechanical properties such as stretchability and elongation atbreak according to the present invention:

EXAMPLES Measurement Methods

The following measurement methods are used to evaluate the parametersgiven in the examples and claims.

Solids Content of Aqueous Suspensions Like Pigment Slurries CelluloseContaining Samples

The suspension solids content (also known as “dry weight”) wasdetermined using a Moisture Analyzer MJ33 from the companyMettler-Toledo, Switzerland, with the following settings: dryingtemperature of 160° C., automatic switch off if the mass does not changemore than 1 mg over a period of 30 s, standard drying of 5 to 20 g ofsuspension.

Moisture Content

Moisture content (wt. %)=100 (wt. %)−solids content (wt. %)

Particle Size of Mineral Particles

The weight median particle size d₅₀ as used herein, as well as the topcut d₉₈ is determined based on measurements made by using a Sedigraph™5120 instrument of Micromeritics Instrument Corporation. The method andthe instruments are known to the skilled person and are commonly used todetermine grain size of fillers and pigments. The measurement wascarried out in an aqueous solution comprising 0.1 wt.-% Na₄P₂O₇. Thesamples were dispersed using a high speed stirrer and supersonics. Forthe measurement of dispersed samples, no further dispersing agents wereadded.

Fiber Length Measurement

A length weighted. average fiber length was determined with a Kajaani FS200 (Kajaani, Electronics Ltd, now Valmet, Finland). The method and theinstrument are known to the skilled person and are commonly used todetermine fiber morphology parameters. The measurement was carried outsolids content of ca. (0.010 wt.-%.

Freeness Tester (Schopper Riegler)

The Schopper-Riegler degree (SR) was measured according to theZelleheming Merkblatt V/7/61 and standardized in ISO 5267/1,

Brookfield Viscosity

The Brookfield viscosity of the aqueous suspensions was measured onehour after the production and after one minute of stirring at 25° C. ±1°C. at 100 rpm by the use of a Brookfield viscometer type RVT equippedwith an appropriate disc spindle, for example spindle 1 to 6.

Light Microscopy to Distinguish Between MFC Types

Micrographs were taken with a light microscope using transmitted lightand bright field method.

Film Forming Device: “Scandinavian Type” Laboratory Sheets

An apparatus as described in SCAN-CM64:00 “Preparation of laboratorysheets for physical testing” was used, some modifications (J. Rantanenet al., “Forming and dewatering of a microfibrillated cellulosecomposite paper”, BioResources 10(2), 2015, pages 3492-3506) werecarried out.

Film Forming Device: “Rapid Kőthen Type” Laboratory Sheets

An apparatus as described in ISO 5269/2 “Preparation of laboratorysheets for physical testing—Part 2: Rapid Kőthen method” was used, somemodifications were applied, see the methods section “MFC fillercomposite films produced with “Rapid Kőthen Type” laboratory sheetformer” for more details.

Tensile Tester

A L&W Tensile Strength Tester (Lorentzen & Wettre, Sweden) was used fordetermination of the elongation at break according to proceduresdescribed in ISO 1924-2.

3D Forming Equipment and Procedure

A Laboratory Platen Press Type P 300 (Dr. Collins, Germany) was used forforming. Pressure, temperature, and pressing time were adjustedaccordingly. Two aluminum dies were used. A first form with outerdimensions of 16 cm×16 cm×2.5 cm and a female die part representing acircular segment with a diameter of 10 cm and a depth of 1 cmrepresenting linear stretch levels of ca. 3%. A second form with outerdimensions of 16 cm×16 cm×3.5 cm and a female die part representing acircular segment with a diameter of 10 cm and a depth. of 2 cm,representing linear stretch levels of ca. 10%.

Flexible rubber plates with the dimensions 20 cm×20 cm×1 cm made of EPDM(ethylene propylene diene monomer rubber)

1. Material Compound of Microfibrillated Cellulose (MFC) and Filler

A compound of microfibrillated cellulose (MFC) and filler was obtainedby treatment of 40 wt. % enzymatically (Buckman Maximyze 2535) andmechanically (disk refiner, to a freeness of >60° SR) pre-treateddissolving pulp together with 60 wt. % GCC filler (Hydrocarb®60) at asolids content of 55% in a co-rotating twin screw extruder. The qualityof the micro fibrillation is characterized with the microscopic image inFIG. 1 .

Microfibrillated Cellulose (MFC) Without Filler

A microfibrillated cellulose (MFC) as characterized with the microscopicimage in FIG. 2 was used. It was available as a suspension with 3.8 wt.% solids content.

Hardwood Pulp

Once dried market eucalyptus pulp with a length weighted average fiberlength of 0.81 mm.

Softwood Pulp

Once dried softwood pulp (pine a length weighted average fiber length of2.39 mm.

GCC, Hydrocarb®60 (Available from Omya International AG, Switzerland)

A dispersed ground calcium carbonate (GCC) pigment slurry with 78 wt. %solids content and a weight median particle size d₅₀ of 1.6 μm was used.

PCC, Syncarb®F0474 (Available from Omya International AG, Switzerland)

A non-dispersed precipitated calcium carbonate (PCC) pigment slurry with15 wt. % solids content and a weight median particle size d₅₀e of 2.7 μmwas used.

Percol®1540, BASF (Germany) 2.Methods

Preparing microscopy samples of microfibrillated cellulose MTV) producedin the presence of filler

A small sample (0.1 g) of wet (ca. 55 wt. %) MFC-filler-compound(described in the material section) was placed into a glass beaker, and500 ml of deionized water were added. A kitchen blender was used toassist in separating fibres and calcium carbonate particles. 2 ml of 10wt. % hydrochloric acid were then added to dissolve the calciumcarbonate, then the resulting mixture was mixes with the kitchen blenderfor 2 minutes. A few drops of this suspension was given on a glassmicroscope slide and dried in an oven at 120° C.

Preparing Microscopy Samples of MFC

Approximately 1 g of microfibrillated cellulose (MFC) without filler asdescribed above in the material section (solids content of 3.8 wt.-%)was placed into a glass beaker, and 500 ml deionized water were added..A kitchen blender was used for 2 minutes to separate the fibermaterial. A few drops of this suspension were given on a glassmicroscope slide and dried in an oven at 120° C.

Preparation of Hardwood Pulp

Once dried eucalyptusus pulp was disintegrated according to ISO 5263-1and diluted to a solids content of 1.5 wt.-%. No refining was applied.

Preparation of Refined Hardwood Pulp

Once dried eucalyptus pulp was disintegrated according to ISO 5263-1 anddiluted to a solids content of 3 wt.-%. A laboratory disk refiner(Escher Wyss, now Voith, Germany) was used to prepare eucalyptusus pulpwith a freeness of 30° SR.

Preparation of Softwood Pulp

Once dried softwood pulp was disintegrated according to ISO 5263-1 anddiluted to a solids content of 1.5 wt.-%. No refining was applied.

Preparation of Refined Softwood Pulp

Once dried softwood pulp was disintegrated according to ISO 5263-1 anddiluted to a solids content of 1.5 wt.-%. A laboratory disk refiner(Escher Wyss, now Voith, Germany) was used to prepare softwood pulp witha freeness of 25° SR.

Preparing Furnish for Film Forming Without MFC

According to the formulations based on dry weight, hardwood pulp orhardwood. pulp or softwood pulp or refined softwood pulp, eventual GCCand/or PCC particles as well as deionized water to obtain a final solidscontent of 1 wt. % wore prepared in high shear conditions (Pendraulik,LD 50 Labordissolver, Pendraulik, Germany) with a mixing time of 15minutes.

Preparation of Liquid Suspension of the MFC Filler Compound

Deionized water was added to the compound with a solids content of 55wt. % in a quantity to obtain 10 wt. % solids content. High shear mixing(Pendraulik, LD 50 Labordissolver, Pendraulik, Germany) was applied for15 minutes to disperse the compound, followed by further dilution withlionized water to a desired solid content level (5 wt.-%, 4 wt.-%, 2.5wt.-%, 1 wt.-%) again with a 15 minutes high shear mixing step(Pendraulik, 2000 rpm).

Preparation of Furnish for Film Forming with MFC Filler Compound

According to the formulations based on dry Weight, mixtures of the MFCfiller compound suspension with 1 wt.-%, solids content, hardwood pulpor softwood pulp and deionized water to obtain a final solids content of1 wt.-% were prepared in high shear conditions (Pendraulik, LD 50Labordissolver, Pendraulik, Germany) with a mixing time of 15 minutes.

Preparation of MFC Suspension Without Filler

Deionized water was added to the MFC, suspension in order to obtaindesired solid content levels (2 wt.-%, 1 wt.-%), high shear mixing(Pendraulik, LD 50 Labordissolver, Pendraulik, Germany) was applied for15 minutes to ensure proper mixing.

Preparation of Furnish for Film Forming with MFC Without Filler

According to the formulations based on dry weight, mixtures containingWC, PCC and/or GCC, eucalyptus pulp or softwood pulp as well asdeionized water to obtain a final solids content of 1% were prepared inhigh shear conditions (Pendraulik, LD 50 Labordissolver, Pendraulik.,Germany) with a mixing time of 15 minutes.

MFC Filler Composite Films Produced with “Scandinavian Type” LaboratorySheet Former

A modified “Scandinavian Type” laboratory sheet former was used toproduce films. An according quantity of the prepared furnish to obtain afilm weight of usually 200 g/m² was filled into the upper section whichwas tightly connected to a membrane as top part of a lower section. Thetop section was closed with a hood and an overpressure of 0.5 bar wasapplied to accelerate dewatering through the membrane. No agitation orfurther dilution was used. After forming the sheets were prepared asknown in the art between two blotting papers and then pressed for 260seconds at 420 kPa. A. further hot press step with four sheets placedbetween two blotting papers and a temperature of 130° C. as well as apressure of 95 kPa was used to dry the sheets. For physical testing, thesheets were placed in a conditioned room, for forming a wettingprocedure was applied.

MFC Filler Composite Films Produced with “Rapid Kőthen Type” LaboratorySheet Former

A sheet forming procedure according to ISO 5269/2 “Preparation oflaboratory sheets for physical testing—Part 2: Rapid Kőthen method” wasused with the following modifications: a wire with a mesh width of 50 μmwas used.. No water for dilution was added. No air for mixing was used.5 seconds after filling the dewatering valve was opened and vacuum wasapplied for 25 seconds The sheets were pressed with Sheet Press (PTI,Austria) and then dried between blotting papers at 115 ° C. for 8minutes.

Re-Wetting Sheets for Forming Trials

Based on the present moisture content (100—solids content in wt. %), adesired amount of deionized water to obtain 6.25 wt.-%, 8 wt.-%, 10wt.-%, 15 wt.-% or 20 wt.-% moisture content was sprayed at the MFCfiller composite films by using an aerosol can. MFC filler compositefilms of the same composition and the same moisture level were storedfor 24 hours in a closed plastic bag to ensure homogeneous distributionof humidity.

3D Forming

For 3D forming a stack has to be prepared, from bottom to top: at firstthere is the bottom part of the platen press, followed by the aluminumdie with the mold facing up, the sheet/film/material to be formed, a.pile of rubber plates (3-4 for the 1 cm deep form, 5-6 for the 2 cm deepform) and finally the top part of the platen press. In the press used,the bottom part was moving and could be heated to a desired temperature.Before starting forming trials, the according die was placed in theheated press to get the desired temperature. Pressure, process dynamics(speed and time), temperature have to be adjusted accordingly.

3. Experiments

a) Viscosities of MFC suspensions

TABLE 1 Solids Brookfield content of Spindle for Viscosity (atsuspension Brookfield 100 rpm and Sample [wt.-%] mesaurement 25° C.) MFCfiller 10 No. 4 730 mPas compound suspension MFC filler 5 No. 2 50.0mPas compound suspension MFC filler 2.5 No. 1 19.5 mPas compoundsuspension MFC without filler 3.8 Not measurable MFC without filler 2No. 6 1 800 mPas MFC without filler 1 No. 4 470 mPasb) MFC filler composite sheet material properties at different moisturelevels

The properties of the obtained sheet materials are also shown in FIG. 3.

TABLE 2 normalized stretch Elongation Elongation increase per at break,at break, level of 10% 20% moisture [% Formulation m.c.^([1]) m.c.^([1])per percent] Hardwood, 200 g/m² 2.1% 2.5% 0.04 Hardwood (refined), 200g/m² (A) 3.0% 4.2% 0.12 Softwood (refined), 200 g/m² (B) 4.4% 5.6% 0.1280 wt. % Softwood (refined) + 3.6% 4.1% 0.05 20 wt. % GCC, 200 g/m² (C)80 wt. % Softwood (refined) + 3.3% 4.7% 0.14 20 wt. % PCC, 200 g/m² (D)60 wt. % Softwood (refined) + 3.3% 4.6% 0.13 40 wt. % PCC, 200 g/m² (E)80 wt. % Softwood (refined) + 3.3% 4.6% 0.13 20 wt. % PCC, 100 g/m² (F)5 wt. % Hardwood, 30 wt. % 7.3% 12.3%  0.5 MFC, 65 wt. % PCC, 200 g/m²(G) 5 wt. % Hardwood, 45 wt. % 7.1% 10.2%  0.31 MFC, 50 wt. % PCC, 200g/m² (H) 20 wt. % Hardwood, 30 wt. % 4.9% 7.5% 0.26 MFC, 50 wt. % PCC,200 g/m2 (I) ^([1])m.c.: moisture content

c) 3D Forming Experiments (1) 3D Forming Parameters

“Scandinavian type” laboratory sheets. Lower pressure in formingbeneficial.

TABLE 3 3 D forming Molding Formulation parameters depth Result 90 wt. %MFC-filler compound, 10 bar, 1 cm cracked 10 wt. % Hardwood, 200 g/m²,10 s, 8% m.c. ^([1]) 70° C. 90 wt. % MFC-filler compound, 10 bar, 1 cmcracked 10 wt. % Hardwood, 200 g/m², 7 s, 8% m.c. ^([1]) 120° C. 90 wt.% MFC-filler compound, 3.8 bar, 1 cm good 10 wt. % Hardwood, 200 g/m²,20 s, 8% m.c. ^([1]) 70° C. 90 wt. % MFC-filler compound, 3.8 bar, 1 cmgood 10 wt. % Hardwood, 200 g/m², 10 s, 8% m.c. ^([1]) 120° C. ^([1])m.c.: moisture content

(2) Reference Samples

“Rapid Kőthen type” laboratory sheets.

TABLE 4 3 D forming Molding Formulation parameters depth Result RefinedHardwood, 0.05 wt. % Percol ® 3.8 bar, 1 cm cracked 1540 based on totaldry weight of cellulose 10 s, material, 200 g/m², 8% m.c. ^([1]) 120° C.80 wt. % refined Hardwood, 20 wt. % GCC, 3.8 bar, 1 cm cracked 0.05 wt.% Percol ® 1540 based on total dry 10 s. weight of cellulose materialand inorganic 120° C. filler material, 200 g/m², 8% m.c. ^([1]) RefinedSoftwood, 0.05 wt. % Percol ® 1540 3.8 bar, 1 cm good based on total dryweight of cellulose 10 s, material, 200 g/m², 8% m.c. ^([1]) 120° C. 80wt. % refined Softwood, 20 wt. % GCC, 3.8 bar, 1 cm cracked 0.05 wt. %Percol ® 1540 based on total dry 10 s, weight of cellulose material andinorganic 120° C. filler material, 200 g/m², 8% m.c. ^([1]) ^([1]) m.c.:moisture content

(3) Compound Series 1, Basic Conditions

“Scandinavian type” laboratory sheets.

TABLE 5 3 D forming Molding Formulation parameters depth ResultHardwood, 200 g/m², 3.8 bar, 1 cm cracked 8% m.c. ^([1]) 10 s, 120° C. 5wt. % Hardwood, 30 wt. 3.8 bar, 1 cm good % MFC, 65 wt. % PCC, 10 s, 200g/m², 8% m.c. ^([1]) 120° C. 5 wt. % Hardwood, 45 wt. 3.8 bar, 1 cm o.k.% MFC, 50 wt. % PCC, 10 s, cracking 200 g/m², 8% m.c. ^([1]) 120° C.starting 20 wt. % Hardwood, 30 wt. 3.8 bar, 1 cm good % MFC, 50 wt. %PCC, 10 s, 200 g/m², 8% m.c. ^([1]) 120° C. ^([1]) m.c.: moisturecontent

(4) Compound Series 2, Forced Conditions and 15 wt. % Moisture Content

“Scandinavian type” laboratory sheets.

TABLE 6 3 D forming Molding Formulation parameters depth ResultHardwood, 200 g/m², 3.8 bar, 2 cm cracked 15% m.c. ^([1]) 10 s, 120° C.5 wt. % Hardwood, 30 3.8 bar, 2 cm o.k., wt. % MFC, 65 wt. % 10 s, notfully PCC, 200 g/m², 15% 120° C. formed m.c. ^([1]) ^([1]) m.c.:moisture content(5) Compound series 3, Forced Conditions and 20 wt. % Moisture Content

“Scandinavian type”laboratory sheets.

TABLE 7 3 D forming Molding Formulation parameters depth ResultHardwood, 3.8 bar, 2 cm cracked 200 g/m², 10 s, 20% m.c. ^([1]) 120° C.5 wt. % Hardwood, 3.8 bar, 2 cm o.k., 30 wt. % MFC, 65 10 s, not fullywt. % PCC, 200 120° C. formed g/m², 20% m.c. ^([1]) ^([1]) m.c.:moisture content

(6) Compound Series 4, Forced Conditions, Different Compositions at 10wt. % Moisture Content

“Scandinavian type” laboratory sheets.

TABLE 8 3 D forming Molding Formulation parameters depth Result 5 wt. %Hardwood, 30 6.0 bar, 2 cm cracked wt. % MFC, 65 wt. % 10 s, PCC, 200g/m², 10% 120° C. m.c. ^([1]) 5 wt. % Hardwood, 45 6.0 bar, 2 cm crackedwt. % MFC, 50 wt. % 10 s, PCC, 200 g/m², 10% 120° C. m.c. ^([1]) 20 wt.% Hardwood, 30 6.0 bar, 2 cm cracked wt. % MFC, 50 wt. % 10 s, PCC, 200g/m², 10% 120° C. m.c. ^([1]) ^([1]) m.c.: moisture content

(7) Compound Series 5, Forced Conditions, Different Compositions at 20wt. % Moisture Content

“Scandinavian type” laboratory sheets.

TABLE 9 3 D forming Molding Formulation parameters depth Result 5 wt. %Hardwood, 30 wt. 6.0 bar, 2 cm good % MFC, 65 wt. % PCC, 10 s, 200 g/m²,20% m.c. ^([1]) 120° C. 5 wt. % Hardwood, 45 wt. 6.0 bar, 2 cm cracked %MFC, 50 wt. % PCC, 10 s, 200 g/m², 20% m.c. ^([1]) 120° C. 20 wt. %Hardwood, 30 wt. 6.0 bar, 2 cm o.k, % MFC, 50 wt. % PCC, 10 s, not fully200 g/m², 20% m.c. ^([1]) 120° C. formed ^([1]) m.c.: moisture content

1-18. (canceled)
 19. 3D-formable sheet material, characterized bycomprising: (a) a cellulose material in an amount from 15 to 55 wt.-%,based on the total dry weight of the 3D-formable sheet material, whereinthe cellulose material is a cellulose material mixture comprising: (i)microfibrillated cellulose in an amount of ≥55 wt.-%, based on the totaldry weight of the cellulose material mixture, and (ii) cellulose fibresin an amount of ≤45 wt.-%, based on the total dry weight of thecellulose material mixture, and the sum of the amount of themicrofibrillated cellulose and the cellulose fibres is 100 wt.-%, basedon the total dry weight of the cellulose material mixture, and (b) atleast one particulate inorganic filler material in an amount of 45 wt.-%to 85 wt.-%, based on the total dry weight of the 3D-formable sheetmaterial, wherein the sum of the amount of the cellulose material andthe at least one particulate inorganic filler material is 100.0 wt.-%,based on the total dry weight of the cellulose material and the at leastone particulate inorganic filler material; wherein the 3D-formable sheetmaterial has: (x) a normalized stretch increase per level of moisturecontent in the range from 0.15 to 0.7% per percent moisture, and (y) anelongation at break of at least 6%, and (z) a sheet weight from 50 to500 g/m².
 20. 3D-formable sheet material, according to claim 19,characterized in that the microfibrillated cellulose has been obtainedby microfibrillating a cellulose fibre suspension in the absence orpresence of fillers and/or pigments, wherein the cellulose fibres of thecellulose fibre suspension are selected from the group consisting ofspruce pulp, pine pulp, eucalyptus pulp, birch pulp, beech pulp, maplepulp, acacia pulp, hemp pulp, cotton pulp, bagasse and straw pulp andrecycled fiber material, and any mixtures thereof.
 21. 3D-formable sheetmaterial, according to claim 19, characterized in that the cellulosefibres: (a) are selected from the group consisting of spruce fibres,pine fibres, eucalyptus fibres, birch fibres, beech fibres, maplefibres, acacia fibres, hemp fibres, cotton fibres, bagasse and strawfibres, recycled fiber material and mixtures thereof, and/or (b) have alength weighted average fibre length from 500 μm to 3000 μm. 22.3D-formable sheet material, according to claim 19, characterized in thatthe at least one particulate inorganic filler material is at least oneparticulate calcium carbonate-containing material.
 23. 3D-formable sheetmaterial, according to claim 22, characterized in that the at least oneparticulate calcium carbonate-containing material is precipitatedcalcium carbonate.
 24. 3D-formable sheet material, according to claim23, characterized in that the precipitated calcium carbonate is selectedfrom one or more of the group consisting of aragonitic, vateritic andcalcitic mineralogical crystal forms.
 25. 3D-formable sheet material,according to claim 22, characterized in that least one particulatecalcium carbonate-containing material is dolomite.
 26. 3D-formable sheetmaterial, according to claim 22, characterized in that the at least oneparticulate calcium carbonate-containing material is at least one groundcalcium carbonate material.
 27. 3D-formable sheet material, according toclaim 26, characterized in that the at least one ground calciumcarbonate-containing material is selected from the group consisting ofmarble, chalk, limestone and mixtures thereof.
 28. 3D-formable sheetmaterial, according to claim 19, characterized in that the at least oneparticulate inorganic particulate inorganic material comprises bothprecipitated and ground calcium carbonate materials.
 29. 3D-formablesheet material, according to claim 19, characterized in that the atleast one particulate inorganic filler material has: (a) a weight medianparticle size d50 from 0.1 to 20.0 μm, and/or (b) a specific surfacearea of from 0.5 to 200.0 m<2>/g as measured by the BET nitrogen method.30. Process for the preparation of a 3D-formed article, characterized inthat the process comprising the steps of: (a) providing the 3D-formablesheet material as defined in any one of claims 1 to 4, and (b) formingthe 3D-formable sheet material into a 3D-formed article, by a methodselected from the group consisting of thermoforming, vacuum forming,air-pressure forming, deep-drawing forming, hydroforming, sphericalforming, press forming and vacuum/air-pressure forming.
 31. Process,according to claim 30, characterized in that the 3D-formable sheetmaterial has been obtained by: (i) providing a cellulose material, asdefined in any one of claims 19 to 22, and (ii) forming a presheetconsisting of the cellulose material of step (i), and (iii) drying thepresheet of step (ii) into a 3D-formable sheet material.
 32. Process,according to claim 31, characterized in that the cellulose material ofstep (i) is combined with at least one particulate inorganic fillermaterial, wherein the at least one particulate inorganic filler materialis at least one particulate calcium carbonate-containing material. 33.Process, according to claim 32, characterized in that the at least oneparticulate calcium carbonate-containing material is precipitatedcalcium carbonate.
 34. Process, according to claim 33, characterized inthat the precipitated calcium carbonate is selected from one or more ofthe group consisting of aragonitic, vateritic and calcitic mineralogicalcrystal forms.
 35. Process, according to claim 32, characterized in thatthe at least one particulate calcium carbonate-containing material isdolomite.
 36. Process, according to claim 32, characterized in that theat least one particulate inorganic particulate inorganic material is atleast one ground calcium carbonate material.
 37. Process, according toclaim 36, characterized in that the at least one ground calciumcarbonate-containing material is selected from the group consisting ofmarble, chalk, limestone and mixtures thereof.
 38. Process, according toclaim 32, characterized in that the at least one particulate inorganicparticulate inorganic material comprises both precipitated and groundcalcium carbonate materials.
 39. Process, according to claim 32,characterized in that the cellulose material of step (i) is combinedwith at least one particulate inorganic filler material, wherein the atleast one particulate inorganic filler material has: (a) a weight medianparticle size d50 from 0.1 to 20.0 μm, and/or (b) a specific surfacearea of from 0.5 to 200.0 m<2>/g, as measured by the BET nitrogenmethod.
 40. Process, according to claim 32, characterized in that: (i)the cellulose material is provided in form of an aqueous suspensioncomprising the cellulose material in a range from 0.2 to 35 wt.-%,and/or (ii) the at least one particulate inorganic filler material isprovided in powder form, or in form of an aqueous suspension comprisingthe particulate inorganic filler material in an amount from 1 to 80 wt.%, based on the total weight of the aqueous suspension.
 41. Process,according to claim 32, characterized in that the cellulose material is acellulose material mixture comprising microfibrillated cellulose thathas been obtained by microfibrillating a cellulose fibre suspension inthe absence of fillers and/or pigments, wherein the microfibrillatedcellulose is in form of an aqueous suspension having a Brookfieldviscosity in the range from 1 to 2000 mPa·s at 25° C., at amicrofibrillated cellulose content of 1 wt. %, based on the total weightof the aqueous suspension.
 42. Process, according to claim 32,characterized in that the cellulose material is a cellulose materialmixture comprising microfibrillated cellulose that has been obtained bymicrofibrillating a cellulose fibre suspension in the presence offillers and/or pigments, wherein the microfibrillated cellulose is inform of an aqueous suspension having a Brookfield viscosity in the rangefrom 1 to 2000 mPa·s at 25° C., at a microfibrillated cellulose contentof 1 wt. %, based on the total weight of the aqueous suspension. 43.Process, according to claim 30, characterized in that the processfurther comprises a step (c) of moisturizing the 3D-formable sheetmaterial provided in step (a) to a moisture content of 2 to 30 wt.-%,based on the total dry weight of the 3D-formable sheet material, beforeand/or during process step (b).
 44. Process, according to claim 30,characterized in that 3D-formed article is selected from the groupconsisting of a packaging container, food container, blister pack, andfood tray.
 45. Use of a 3D-formable sheet material, as defined in anyone of claims 19 to 29 characterized in that it is for 3D-formingprocesses comprising thermoforming, vacuum forming, air-pressureforming, deep-drawing forming, hydroforming, spherical forming, pressforming, or vacuum/air-pressure forming.
 46. 3D-formed article,characterized in that it is preferably a packaging container, foodcontainer, blister pack, food tray, comprising the 3D-formable sheetmaterial, as defined in any one of claims 19 to 29.